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IMSL_BESSJ

IMSL_BESSJ

The IMSL_BESSJ function evaluates a Bessel function of the first kind with real order and real or complex parameters.

This routine requires an IDL Advanced Math and Stats license. For more information, contact your sales or technical support representative.

The IMSL_BESSJ function evaluates a Bessel function of the first kind with real order and real or complex parameters. The data type of the returned value is always complex.

The Bessel function, Jv>(z), is defined as follows:

for:

This function is based on the code BESSCC of Barnett (1981) and Thompson and Barnett (1987). This code computes Jv(z) from the modified Bessel function Iv(z), using the following relation with:

Example


In this example, J0.3 + v–1(1.2 + 0.5i), v = 1, ..., 4 is computed and printed.

z = COMPLEX(1.2, .5)
FOR i = 0, 3 DO PM, IMSL_BESSJ(i + .3, z)
  (	0.773756,   -0.106925)
  (  0.400001,    0.158598)
  ( 0.0867063,   0.0920276)
  ( 0.00844932,  0.0239868)
PM, IMSL_BESSJ(.3, z, Sequence = 4), Title = 'With SEQUENCE:' 
With SEQUENCE:
  (  0.773756,   -0.106925)
  (  0.400001,    0.158598)
  ( 0.0867063,   0.0920276)
  ( 0.00844932,  0.0239868)

Syntax


Result = IMSL_BESSJ(Order, Z [, /DOUBLE] [, SEQUENCE=value])

Return Value


The desired value of the modified Bessel function.

Arguments


Order

Real parameter specifying the desired order. The argument order must be greater than –1/2.

Z

Real or complex parameter for which the Bessel function is to be evaluated.

Keywords


DOUBLE (optional)

If present and nonzero, then double precision is used.

SEQUENCE

If present and nonzero, a one-dimensional array of length n containing the values of the Bessel function through the series is returned by IMSL_BESSJ, where n = NELEMENTS(SEQUENCE). The i-th element of this array is the Bessel function of order (Order + i) at Z for i = 0, ... (n – 1).

Version History


6.4

Introduced



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